Thread cutting tool



Dec. 4. 1934. A. J. FRANCE 1,983,190

THREAD CUTTING TOOL Filed July 28, 1952 I I 6a INVENTOR cg/ fizerzz@umeg Sum in: r

\ Patented Dec. 4, 1934.

THREAD CUTTING TOOL Albert J. Prance, Detroit, Mich., assignor toMurchey Machine & Tool Company, Detroit, Mich., a corporation ofMichigan Application July 28, 1932, Serial No. 625,313

6 Claims.

This invention relates to thread cutting chasers, and more particularlyto an improved thread cutting device adapted to be carried by arotatable head or holder together with one or more other similarchasers, concerning itself specifically with the provision of improvedmeans for adjustably securing the chasers in place.

An object of this invention is provision of strong and novel means forlocking and supporting the 10 chasers.

A further object is provision of novel means for adjusting the positionof the chaser cutting edges to compensate for wear and grinding, whichad- .justing means is of such strength as to easily withstand the fullthrust imposed by engagement of the tool with the work.

'Still further objects will readily occur to those skilled in the artupon reference to the following description and the accompanying drawingin which I Fig. 1 is a sectional view of a chaser block and a chaser,showing the novel chaser adjusting means; k j Fig. 2 is a section takensubstantially on the line 22 of Fig. 1 and looking in the direction ofthe arrows;

Fig. 3 is a side view of a somewhat modified form of chaser; I

Fig. 4 is a side view of a modified form of chaser driving worm wheeland connecting member adapted to cooperate with the modified chasershown in Fig. 3.

Referring to the drawing, it will be seen that a chaser block 24 isprovided carrying on its front 35. face 26a thread cutting chaser 28 ofa form to be described.

The block may be provided with abutment pins as 32 adapted to be engagedby suitable positioning means carried by the head or other support,

(unshown) and beveled as at 42, for engagement.

with an adjusting cam or the like (also unshown) Each chaser 28 isperipherally provided with master thread ribs 50 and is cut away so thata cutting edge 54 is formed. The position of this edge 54 with respectto the central axis of the 'chaser and with respect to the chaser headis extremely important and must be maintained uniform for each chaserwhen several are used. When the cutting edge 54 wears down it must bereground, and the chaser must then be rotated on its axis to return thenew edge 54 to its original position. For this purpose means to rotatethe chaser infinitesimal amounts on its own central 'axis is provided,and will now be described. 55? Chaser 28 is centrally provided with asplined aperture adapting it to fit over the complementarily splinedportion 58 of the hub 62. The hub is provided with an enlarged headportion 60 in the form of a worm wheel, and is rotatably disposed withinthe hollow chaser block 24 in the '9 manner shown so that its splinedportion 58 projects therefrom and into interlocked engagement with theinteriorly splined aperture 56 in the chaser. The extreme end 64 of thehub member is reduced and threaded for reception of the nut 65 66, whichsecures the chaser to the block and fits within the counterbored portion56 of the aperture in the chaser. The enlarged worm whee] portion 60 ofthe hub member fits within a counterbored portion 61' of the aperture 61in 7 the chaser block, so that by tightening the nut 66 the chaser andblock may be clamped together. The thread of the portion 64 ispreferably made so that the nut tightens when turned in the oppositedirection to that in which the chaser must be 7 turned to advance thecutting edge.

A pair of worms 68 disposed within transverse bores 72 of the chaserblock engage the worm wheel 64 to enable rotating the latterinfinitesimal amounts and since the wheel is locked to the g chase, thelatter will also be rotated the same amount, as can be readily observed.

The worms 68 may be provided with inset hex counterbores as 78 wherebythey may be rotated by means of an Allen wrench, or the like.

It will also be observed that after a chaser is adjusted with respect tothe block, the nut 66 may be tightened in order to clamp the chaser tothe block without disturbing the setting or adjustment of the chaser,which may be very accurately fixed by reason of the use of two worms,which enable fixing the position with absolutely no play or looseness tointroduce inaccuracies.

It will further be seen that due to the novel adjustment provided aninfinite number of positions for the cutting edge can be maintained andaccordingly, it is not necessary to grind the cutting edge any more thanis necessary to sharpen it, there being no grinding back for positioningthe cutting edge as is the case with other forms of chasers well knownin the art rotatably adjustable only in steps.

It will further be observed that each chaser is provided with a broadcontinuous peripheral chamfer 80, thus eliminating the necessity ofproviding a new chamfer on the chaser when the cutting edge is beingground.

Any strain on the chaser cutting edge 54 not absorbed by the block 24against which the chaser is clamped is transmittedto the worms 68 thruthe hub and the wheel 64, but: by using two of these in the mannershown, adequate strength to insure their long life is obtained, andsince they are comparatively inexpensive and readily replaceable, thisis unimportant in any event. Maintenance of the chasers in threadcutting machines is thus made a very simple and inexpensive matter.

In Figs. 3 and 4 there is disclosed a modification in which the chaseris provided with integral lugs 92 projecting from its rear surface. Thehub 94 and worm wheel 96 are formed as a unit, and the hub carries slotsor crown clutch teeth 98 with which the lugs are adapted to interfit.The chaser and hub member are axially bored, as at 99 and 100respectively, and may be secured together in position and to the chaserblock by means of a nut and bolt (not shown).

Now having described the invention and the preferred embodiment thereof,it is to be understood that said invention is to be limited, not to thespecific details herein set forth, but only by the scope of the claimswhich follow:

What I claim is:

1. In a chaser head construction, a chaser block, a chaser shaftjournaled in the block and having an end exposed at the front of theblock, a chaser, screw-threaded securing means for securing the chaserupon the front of the block and to said end of the shaft, said securingmeans being accessible from-the front of the chaser and being adaptedwhen tightened to clamp the chaser against the block, and meansiorrotating the chaser to adjust the position of its cutting edges, saidmeans including a worm wheel attached to said chaser shaft, and a wormcarried by the block and engaging the worm wheel.

2. In a chaser head construction, a chaser block, a chaser shaftjournaled in said block and having a free splined and screw-threadedextremity at the front of the block, a complementarily splined chasermounted on said shaft in front of the block, screw-threaded meansaccessible from the front of the chaser for securing the latter upon theshaft and clamping it against the block, and means for rotating theshaft and so the chaser to adjust the position of the chaser cuttingedges, including a worm wheel connected to the shaft, and a worm mountedin the block and engaging the worm wheel.

3. In a chaser head construction, a chaser block, a chaser, a combinedchaser shaft and clamping bolt journaled in said block and carrying thechaser upon its front end, the chaser overhanging the block, a headportion carried by said combined shaft and bolt member and arrangedbehind a part of the block, and means engaging said head for rotatingthe latter and so the chaser shaft and chaser to adjust the position ofthe chaser cutting edges, and means for clamping the head and chaseragainst opposite surfaces of the block.

4. In a chaser head construction, a chaser block, a chaser shaftjournaled in the block and having a free screw threaded extremity at thefront of the block, a chaser, means for securing the chaser to the shaftin any of various positions and for clamping the chaser against theblock, including screw threaded means manipulatable from the front ofthe chaser and cooperatively engageable with the screw threadedextremity of the shaft, a worm pinion carried by a rear portion of saidshaft, and a worm journaled in the block and engaging the pinion toenable turning the shaft and so turn the chaser with respect to theblock to change the position of the chaser cutting edge.

5. In a chaser head construction, a chaser block, a combined clampingbolt and hub member journaled in the block and having an exposed endaccessible from the front of the block, a chaser, a head portion carriedby said combined bolt and hub member and overhanging a rearwardly facingsurface of the block, screw threaded means for securing the chaser tothe hub and for clamping the chaser to the front face of the block, apinion carried by said head portion of the combined bolt and hub member,and a worm in the block engaging the pinion to rotate the latter and sothe chaser and hub assembly as a unit with respect to the block foradjusting the position of the chaser cutting edges.

6. In a chaser head construction, a chaser block, a combined supportinghub and clamping bolt journaled in the block, a chaser, screw threadedmeans for securing the chaser to the end of the hub, a head portioncarried by said combined hub and bolt, a pinion carried by said head,the hub and chaser being provided with selectively interengageableportions whereby they are nonrotatable with respect to each other whenassembled, and a worm in the block engaging the.

pinion to rotate the same and so the hub and chaser assembly as a unitwith respect to the block, for adjusting the position of the chasercutting edges. 1

.ALBERT J. FRANCE.

